The techniques of rapid reaction kinetics will be employed to study the mechanism of oxygen binding to normal and abnormal hemoglobins. The proposed studies are a continuation of an effort to obtain elementary rate and equilibrium constants for individual subunits within tetrameric hemoglobin and to determine quantitatively the effect of organic phosphates on each subunit in liganded hemoglobin. Elementary step rate parameters will be determined by relaxation kinetics. A recently observed DPG-induced spectroscopic change in liganded hemoglobin will be investigated. The mechanism by which N-terminal specific modifications of hemoglobin-S inhibit gelation will be studied after isolation of various N-terminal modified tetramer intermediates. A method will be developed for measuring the rate of the initial stages of HbS association.